[cyb-59] JS fetch auth library
[cyb-59] gruntfile correction
[cyb-59] removed wrong grunt dependency
[cyb-59] httpsync module replaced with http-sync.
[cyb-59] Changes to make library interface more consistent with Java library API. Changes according to PR`s comments
[cyb-59] tests corrected
[cyb-59] docs updated
[cyb-59] changes for PR comments
[cyb-59] changes according to PR comments
[cyb-59] tests corrected. getTokenImpl improved.
[cyb-59] getRequiredCredentials, invalidateToken added
[cyb-59] Tests, docs improved.
Merge pull request #48 from cybervisiontech/cyb-59

[cyb-59] JS fetch auth library

Merging. Opened a JIRA to possibly change requests from sync to asynchronous: https://issues.cask.co/browse/CDAP-597